FLP is a set of two neurons, which have ciliated endings situated immediately dorsal to the lateral inner labial sensilla in the head but have no associated sheath or socket cells. They have flattened processes in this region of the cilium (figure 1). The processes from the endings run down in the lateral labial process bundles but do not enter the nerve ring along with the other processes; instead they continue posteriorly and join up with their cell bodies laterally. A branch comes off this process anterior to the cell body and runs backwards alongside the dorsal muscle quadrants. Small processes emanate from this branch and run underneath the muscles for a short distance (e). Processes from the cell bodies enter the retro-vesicular ganglion via the deirid commissures and run together anteriorly, near the middle of the cord, ending before the nerve ring is reached. Most of the synaptic interactions occur in this region of the cord but there are also a few synapses on the lateral processes in the vicinity of the nerve ring (c). The main synaptic outputs are to AVA (a), AVD (a, b), AVB (b), AIB and ADE (c) in various dyadic combinations. There is possibly some synaptic input from ADE. There are gap junctions to RIH (d), AVD and itself. Magnifications: (a, c, d) x 25500, (b) x 17000.
Web adaptation, Thomas Boulin, for Wormatlas, 2001, 2002